In this paper, we propose a blockchain inspired internet-of-things architecture for creating a transparent food supply chain. The architecture uses a proof-of-object based authentication protocol, which is analogous to the cryptocurrency’s proof-of-work protocol. The complete architecture was realized by integrating a RFID based sensor at the physical layer and blockchain at the cyber layer. The RFID provides a unique identity of the product and the sensor data, which helps in real time quality monitoring. For this purpose, a small feature size 900 MHz RFID coupled sensor was fabricated and demonstrated for real time sensor data acquisition. The blockchain architecture aids in creating a tamper-proof digital database of the food packages at each instance. A detailed security analysis was performed to investigate the vulnerability of the proposed architecture under different types of cyber attacks.

The ultimate goal of this paper is to print radio frequency (RF) and microwave structures using a 3-D platform and to pattern metal films on nonplanar structures. To overcome substrate losses, air core substrates that can readily be printed are utilized. To meet the challenge of patterning conductive layers on complex or nonplanar printed structures, two novel self-aligning patterning processes are demonstrated. One is a simple damascene-like process, and the other is a lift-off process using a 3-D printed lift-off mask layer. A range of microwave and RF circuits are designed and demonstrated between 1 and 8 GHz utilizing these processes. Designs are created and simulated using Keysight Advanced Design System and ANSYS High Frequency Structure Simulator. Circuit designs include a simple microstrip transmission line (T-line), coupled-line bandpass filter, circular ring resonator, T-line resonator, resonant cavity structure, and patch antenna. A commercially available 3-D printer and metal sputtering system are used to realize the designs. Both simulated and measured results of these structures are presented.

This paper presents the fabrication and characterization of radio frequency (RF) and microwave passive structures on an air substrate using additive manufacturing (3-D printing). The air substrate is realized by 3-D printing RF structures in two separate pieces and snapped together face to face using a LEGO-like process. Spacers printed on the periphery provide the desired air substrate thickness. Metal patterning on nonplanar printed plastic structures is carried out using a damascene-like process. Various RF structures such as low dispersion transmission line, T-line resonator, high-gain patch antenna, slot antenna, and cavity resonator are demonstrated using this process. Good performance is achieved; for example, measured 50-Ω transmission line shows low loss of 0.17 dB/cm at 4 GHz, and a patch antenna (center frequency of 4.5 GHz) shows gain and bandwidth of 7.6 dB and 0.2 GHz, respectively. Details of both measured and simulation results are presented.

In this paper, an RFID coupled batteryless digital sensor tag is proposed for detecting Ammonia in packaged food. An interdigitated capacitive sensor coated with a thin film of Polyaniline(PANi) that has a higher affinity towards Ammonia is used as a sensing element. To determining the sensitivity of the sensing element, (i) Wireless Near field Short range technique (Capacitance change), and (ii) Direct Probing (Resistance change) techniques are evaluated. The short range technique consists of an inductor coupled to the interdigitated capacitor to form an LC tank and the resonance (capacitance) change due to Ammonia loading is read using a pick-up coil. The direct probe technique uses two wires to measure the resistance across the interdigitated capacitor as a function of Ammonia concentration. Among the two techniques, for demonstrating long range sensing with digitization, direct probing is chosen as this is more stable and can detect a minimum of 3 ppm of Ammonia at room temperature with a response time of 30 min and recovery time of 60 min. The long range approach consists of an RF front end with an antenna and an energy harvester and a low power digital backend that converts the sensor data into bits for transmission. The entire system is passive in nature and does not require an external power supply for operation making it a low cost and simple solution that can be easily integrated as part of the RFID infrastructure. The ID integrated sensor tags are used for a myriad of quality control applications across the food supply chain spectrum.

A wireless antibody-free biosensor for rapid detection of pathogenic bacteria in milk was developed using dextrincapped gold nanoparticles (d-AuNP) as markers. The developed system consists of an interdigitated capacitor coupled to an inductor forming an inductor-capacitor (LC) resonant tank; a “Smart” vial onto which E. coli C3000 suspended in milk matrix adheres and are labeled with d-AuNP markers; and a wireless pick up coil. Detection is based on impedance loading of the interdigitated sensor by d-AuNP bound to the pathogenic bacteria. The resonance frequency shift of the LC tank is correlated with the concentration of E. coli cells in the milk. The sensors are field-operable and can detect bacteria counts as low as 5 log CFU/ml within an hour. Spectrophotometry is used to verify the sensitivity of the developed sensor. The resonance frequency of these sensors can be easily designed to match the existing radio frequency identification (RFID) frequency bands. The developed tag holds potential application in detection of a variety of pathogenic bacteria for quality control along the liquid food supply chain.

This paper investigates a step by step design procedure of a hybrid passive wireless sensor. The hybrid sensor measures both the electrical (dielectric constant) and the mechanical (viscosity) properties of liquid, providing a two-factor quality control. The hybrid sensor is based on an inductor-capacitor resonant tank coupled with a magnetoelastic strip. The mechanical and the electrical resonances change as a function of viscosity and dielectric constant, respectively. Two different hybrid sensor designs are investigated: 1) a parallel plate capacitor coupled with a separate amorphous ferromagnetic magnetoelastic strip (Metglas) and 2) a capacitor made using two parallel mounted magnetoelastic strips. The sensors are integrated as part of the “smart vial” making it field operable for food quality monitoring and control. Here, detection of adulteration in extra virgin olive oil is achieved by measuring the change in viscosity and dielectric constant for different adulteration levels. The real part of the dielectric constant for different liquid samples is measured in the frequency range of 3-24 MHz. The hybrid sensor is able to detect adulteration levels below 10% in volume. These sensors can be integrated with passive RFIDs for simultaneous measurement of multiple samples in an array format.